Compare the installation packages
Compare the retained layers in a liner proposal with the demolition and new assembly in a replacement proposal. Establish how the existing base and walls are assessed and who takes responsibility for concealed conditions. Overlaying a surface and rebuilding an enclosure are different scopes even if the finished appearance is similar.
Normalize the proposals
Use the same dimensions, fixtures and enclosure features for both options, then isolate the work that differs. Mark demolition, substrate preparation, connections and finish restoration as included or excluded. Ask each contractor to identify the condition that would change the recommended assembly. This exposes a real scope difference instead of treating two product labels as a complete comparison. Where either option requires specialist fabrication, identify who measures and approves those components before ordering.
What is the key boundary in the comparison?
How much of the original assembly remains and what evidence supports retaining it. The proposal should identify that boundary explicitly, especially around drains, wet substrates and failed connections.
The owner should confirm the proposed service scope and provider availability independently. This guidance does not identify an approved contractor, establish coverage for a specific property or guarantee acceptance of the project.